# Create or update manifest custom field

Adds a new custom field to a manifest or updates an existing one. Custom fields allow storing additional metadata key-value pairs specific to your integration needs.

Endpoint: POST /integration/rest/api/v1/manifest/{manifestExternalId}/custom-field
Version: v1
Security: X-AUTH-KEY

## Path parameters:

  - `manifestExternalId` (string, required)
    Unique external identifier of the manifest
    Example: "MAN-2024-001"

## Request fields (application/json):

  - `fieldKey` (string)
    Unique key (name) of the custom field. This must match the configured field name.

  - `fieldValue` (string)
    Value of the custom field as a string. For numeric fields, send the number as a string.

## Response 400 fields (*/*):

  - `code` (string)
    Error code

  - `message` (string)
    Error message

  - `timeStamp` (integer)
    Timestamp

  - `correlationId` (string)
    Correlation id

## Response 404 fields (*/*):

  - `code` (string)
    Error code

  - `message` (string)
    Error message

  - `timeStamp` (integer)
    Timestamp

  - `correlationId` (string)
    Correlation id

## Response 500 fields (*/*):

  - `code` (string)
    Error code

  - `message` (string)
    Error message

  - `timeStamp` (integer)
    Timestamp

  - `correlationId` (string)
    Correlation id